/**
 * App-wide transcript scroll bridge.
 *
 * Wheel/trackpad events often land on the focused composer (or fail hit-test
 * and fall back to it). Those events never bubble into the transcript
 * ScrollBox, so scroll felt like “walking prompt history” instead of moving
 * the chat. TranscriptView registers its native scrollbox here; App +
 * Composer forward every free wheel event to this port.
 *
 * Selection drag uses the same port for edge autoscroll when the pointer
 * leaves the scrollbox (e.g. over the composer) so “select down” keeps moving.
 *
 * Scroll metrics (lines above / below the viewport) feed the status bar badges
 * that classic Ink showed under the input (`▲ N` / `▼ N`).
 */
export interface TranscriptScrollPort {
    /** Scroll the chat by `dy` rows (negative = up). Returns false if unmounted. */
    scrollBy(dy: number): boolean;
    /** Jump to absolute top of the chat (intro card). */
    scrollToTop(): boolean;
    /** Jump to absolute bottom of the chat (latest message). */
    scrollToBottom(): boolean;
    /** OpenTUI ScrollBox edge autoscroll while drag-selecting. */
    updateAutoScroll(x: number, y: number): void;
    stopAutoScroll(): void;
    /** True when the live port is registered. */
    readonly active: boolean;
    /** Latest lines-above / lines-below metrics (classic status badges). */
    readonly metrics: ScrollMetrics;
    /** Subscribe to metric changes; fires immediately with the current value. */
    onMetrics(listener: (metrics: ScrollMetrics) => void): () => void;
}
/** Classic-parity remaining-line counts for the status strip under the input. */
export interface ScrollMetrics {
    /** Rows of transcript above the viewport (scroll further up to read). */
    readonly linesAbove: number;
    /** Rows of transcript below the viewport (scroll further down to catch up). */
    readonly linesBelow: number;
}
export declare const EMPTY_SCROLL_METRICS: ScrollMetrics;
type Handler = (dy: number) => void;
type JumpHandler = () => void;
type AutoScrollHandler = {
    update(x: number, y: number): void;
    stop(): void;
};
export declare const transcriptScrollPort: TranscriptScrollPort;
/** TranscriptView calls this on mount; returns an unregister function. */
export declare function registerTranscriptScrollPort(next: Handler): () => void;
/** Register absolute top/bottom jumps (g / G). */
export declare function registerTranscriptJumpHandlers(top: JumpHandler, bottom: JumpHandler): () => void;
/** Wire ScrollBox start/update/stop auto-scroll for selection edge scroll. */
export declare function registerTranscriptAutoScroll(next: AutoScrollHandler): () => void;
/**
 * TranscriptView publishes viewport remainder so the status line can show
 * classic `▲ N` / `▼ N` badges under the composer.
 */
export declare function publishTranscriptScrollMetrics(next: ScrollMetrics): void;
export {};